Commonly-owned U.S. patent application No. 08/152,812 filed Nov. 16, 1993 (now U.S. Pat. No. 4,576,211, issued Dec. 19, 1995), and its counterpart commonly-owned copending "divisional" U.S. patent applications Nos. 08/457,479 filed Jun. 1, 1995 (status: pending) and 08/570,230 filed Dec. 11, 1995 (status: pending), all by KHANDROS, disclose methods for making resilient interconnection elements for microelectronics applications involving mounting an end of a flexible elongate core element (e.g., wire "stem" or "skeleton") to a terminal on an electronic component, coating the flexible core element and adjacent surface of the terminal with a "shell" of one or more materials having a predetermined combination of thickness, yield strength and elastic modulus to ensure predetermined force-to-deflection characteristics of the resulting spring contacts. Exemplary materials for the core element include gold. Exemplary materials for the coating include nickel and its alloys. The resulting spring contact element is suitably used to effect pressure, or demountable, connections between two or more electronic components, including semiconductor devices.
Commonly-owned, copending U.S. patent application No. 08/340,144 filed Nov 15, 1994 and its corresponding PCT patent application No. PCT/US94/13373 filed Nov 16, 1994 (WO95/14314, published May 26, 1995), both by KHANDROS and MATHIEU, disclose a number of applications for the aforementioned spring contact elements, and also discloses techniques for fabricating contact pads (contact tip structures) at the ends of the spring contact elements.
Commonly-owned, copending U.S. patent application No. 08/452,255 filed May 26, 1995 and its corresponding PCT patent application No. PCT/US95/14909 filed Nov 13. 1995 (WO96/17278, published Jun. 6, 1996), both by ELDRIDGE, GRUBE, KHANDROS and MATHIEU, disclose additional techniques and metallurgies for fabricating spring contact elements as composite interconnection structures and for fabricating and mounting contact tip structures to the free ends (tips) of the composite interconnection elements.
Commonly-owned, copending U.S. patent application No. 08/558,332 filed Nov 15, 1995 by ELDRIDGE, GRUBE, KHANDROS and MATHIEU, and its corresponding PCT patent application No. US95/14885 filed Nov 15, 1995 by ELDRIDGE, GRUBE, KHANDROS and MATHIEU disclose methods of fabricating resilient contact structures which are particularly well-suited to fabricating spring contact elements directly on semiconductor devices. As used herein, a semiconductor device having spring contact elements mounted thereto is termed a "springed semiconductor device".
Commonly-owned, copending U.S. Provisional patent application No. 60/024,555 filed Aug 26, 1996, by ELDRIDGE, KHANDROS and MATHIEU, and PCT patent application No. US97/08606 filed May 15, 1997 by DOZIER, ELDRIDGE, KHANDROS, MATHIEU and TAYLOR disclose additional contact tip structure metallurgies and structures.
The present invention addresses and is particularly well-suited to making interconnections to modern microelectronic devices having their terminals (bond pads) disposed at a fine-pitch. As used herein, the term "fine-pitch" refers to microelectronic devices that have their terminals disposed at a spacing of less than 5 mils, such as 2.5 mils or 65 .mu.m. As will be evident from the description that follows, this is preferably achieved by taking advantage of the close tolerances that readily can be realized by using lithographic rather than mechanical techniques to fabricate the contact elements.